Deciding on the production system that Boeing adopts for any new aircraft developed to address the niche in the narrowbody market previously filled by the 757 will be a key aspect of its studies to ensure low build costs.

The manufacturer has long been studying the market for 200-300 seater aircraft with a range of 4,000-5,000nm (7,400-9,250km). This category fits between the top of its single-aisle product line currently occupied by the 737-900ER and the bottom end of its 787 widebody family. This market was left vacant when Boeing ended production of the 757 narrowbody in 2004 after just over 1,000 deliveries.

“You’ve always had that challenge of the transition between the single-aisle and the widebody,” Boeing’s marketing vice president Randy Tinseth told Flightglobal at the Singapore air show.

“The 737-900ER/Max 9 covers 95% of the routes flown by a 757 - and Airbus will tell you the same [about the A321]. But there is that 5% that we saw with the 757 that was really game-changing. The 757 brought a unique set of capabilities,” he adds.

Key to the 757’s popularity was its relatively long-range, which enabled it to fly transatlantic operations. “There are airlines that really like that capability across the North Atlantic, and the A321 can’t do that and nor can the Max 9,” says Tinseth.

Tinseth says that Boeing is in the early stages of defining the aircraft to succeed the 757, and central to those studies is how it will be built.

“We’re trying to figure out what that transition airplane looks like, what is the market size and what technologies do you need to incorporate,” he says. “And really importantly, what does the production system look like to make sure you can have cost that makes sense in the market too.”

He adds: “We're working through that and it’s going to take us a while.”

Boeing’s senior vice president global sales John Wojick says that Boeing is in the “study and customer requirement phase” of this category of aircraft and has “an awful lot of discussions to go with our customers”. However he adds that the studies have not yet reached the stage where Boeing has entered detailed discussions with engine suppliers about the powerplant technology that could be adopted for any new 200-300 seater.